Automatic cleaners configured to travel through a water pool for cleaning the pool water surface and/or containment wall surface are well known in the art. Such cleaners include units which operate (1) solely at the wall surface (which shall be understood to include side and floor portions), (2) solely at the water surface, or (3) selectively at the wall surface and water surface (e.g., U.S. Pat. Nos. 5,985,156; 6,039,886; 6,090,219).
Such automatic pool cleaners are generally powered by energy delivered to the cleaner via a flexible elongate conduit, e.g., a pressure hose, a suction hose, an electric wire, etc. The delivered energy functions to propel the cleaner, typically along a substantially random travel path, while pulling the conduit behind it. Regardless of the energy form used, the flexible conduit can on occasion physically interfere with and hinder the cleaner's ability to freely travel through the pool. To avoid such interference, cleaner systems are generally configured to maintain the conduit out of the normal travel path of the cleaner. For example, a conduit used with a wall surface cleaner is generally configured (i.e., effective specific gravity <1.0) to float near the water surface to avoid the cleaner having to climb over the conduit. Water surface cleaners generally use a conduit configured (i.e., effective specific gravity >1.0) to sink to the wall surface, i.e., pool floor, to avoid obstructing the cleaner. Cleaners configured to selectively travel at the water surface and wall surface preferably use a conduit configured to situate the major length of the conduit at a level between the pool water surface and containment wall surface to avoid obstructing the cleaner's movement along its travel path. The desired specific gravity for the conduit can be achieved by an appropriate choice of conduit materials and/or a proper utilization and placement of positive and/or negative buoyancy members (e.g., floats and/or weights) along the conduit length.
Typical prior art conduit assemblies are comprised of one or more elongate flexible sections which form a continuous path extending from a power source, generally via a stationary fitting mounted adjacent to the containment wall, to the cleaner. The conduit should be of sufficient length (typically, 15-45 feet) to enable the cleaner to travel to any point in the pool. A typical conduit for use with a positive pressure fluid power source comprises a hose of axially flexible material having an inner diameter of about ⅜″-1″. A typical conduit for use with a negative pressure (i.e., suction) fluid source comprises an axially flexible hose having an inner diameter of about 1-2″. The smaller diameter pressure hose is typically formed of soft wall material which is able to maintain easy axial flexibility in the pool environment (wet with large temperature excursions) over an extended period of time. The larger diameter suction hose is typically formed of a corrugated wall material which affords axial flexibility.
Typical prior art conduit assemblies include one or more swivels located between the power source and the cleaner to enable the conduit and/or conduit sections to swivel axially to minimize the tendency of the conduit to form persistent coils which can hinder the cleaner's freedom of movement.
Despite the aforementioned efforts to prevent the cleaner from engaging the conduit and efforts to facilitate conduit axial flexibility and axial swivelability, in practice, a typical conduit over an extended period of operation may develop persistent coils and/or knots which can hinder the cleaner's ability to freely and fully travel throughout the pool.
Applicant's PCT Application PCT/US2003/032639 discloses an improved power conduit for use with automatic pool cleaners particularly configured to avoid the formation of persistent coils and/or knots. Whereas prior art conduits are characterized by the use of elongate hoses which exhibit substantially uniform axial flexibility along substantially their entire length, embodiments described in said PCT Application 032639 are configured to restrict axial flexibility to designated locations spaced along the conduit length. Such embodiments are characterized by the use of at least one axially stiff elongate section in combination with axially flexible and axially swivelable means. The axially flexible and axially swivelable means can be implemented in a variety of ways. For example, the desired axially flexible and swivelable behavior can be afforded by an integrated universal joint, e.g., ball, or by separate devices such as a soft hose or a hinge affording axial flexibility and a sleeve swivel affording axial swivelability.
The preferred conduit embodiment disclosed in said PCT Application 032639 is comprised of two or more elongate axially stiff members arranged in series with an axially flexible and axially swivelable means. Axial flexibility is preferably provided by a flexible elongate member and axial swivelability by a sleeve swivel. Multiple elongate stiff members and flexible members are arranged in series to form a length sufficient to extend between a stationary power source fitting and a cleaner configured to travel throughout a water pool. In a preferred implementation for use with a positive pressure power source (e.g., water pump), each stiff elongate member comprises a substantially rigid tube defining a central lumen for carrying a fluid (e.g., water) under positive pressure and each flexible elongate member comprises a soft hose which also defines a central lumen for carrying the positive pressure fluid. The preferred implementation is comprised of alternating rigid tubes and soft hoses connected between a stationary power source fitting and a cleaner. The lengths of the rigid tubes are preferably considerably greater than the lengths of the soft hoses between adjacent rigid tubes. For example, a typical embodiment uses rigid tubes having a length of about four feet, connecting soft hoses having a length of about 1½ feet, and longer proximal and distal soft hose lengths respectively coupled to the power source fitting and to the cleaner.